Compounds containing halogen are among those effective for imparting flame resistance to flammable substrates. In particular, many organic bromine compounds are known agents for compounding flame retardant plastics.
Phosphorus containing compounds also have utility for imparting flame resistance. For example, melamine, phosphate and salts of benzenephosphonic acid and melamine have been suggested as flame retardants (see, U.S. Pat. Nos. 4,061,605 and 4,080,501).
Phosphoramidate esters of dibromoeopentyl glycol useful as flame retardants for polymeric materials have been prepared (see, U.S. Pat. No. 3,887,655).
The requirements for a suitable flame retardant extend beyond the sole ability to impart flame resistance. A flame retardant suitable for plastics must be highly compatible with its base material not only under conditions of use but at the processing stage where the plastic and flame retardant are being compounded.
The environment of temperature and shear forces present in modern plastic milling equipment render some flame retardant compounds unsuitable because of instability, volatility, or a tendency to separate from the base plastic during compounding. The result is often a nonhomogenous product with unacceptable flame retardant characteristics.
It is desirable to develop new flame retardant agents which are effective, stable, and easily compounded into plastic materials with high temperature processing equipment.